1. Technical Field
The present invention relates generally to an improvement on a floor structure of automotive vehicles, and more particularly to a joint structure for joining side sills extending longitudinally of a vehicle body on both sides of a front floor, a rear seat cross member installed on a rear floor connected to the rear of the front floor, and rear side members extending longitudinally of the vehicle body on both sides of the rear floor.
2. Background Art
Japanese Patent First Publication No. 7-165124 teaches a joint structure for floor frame members of an automotive vehicle. In the joint structure, a front end portion of each rear side member is connected along an inner side surface of a rear end portion of one of the side sills. Each end of a rear seat cross member extending in a width-wise direction of a vehicle body passes through one of the rear side members perpendicular thereto and connects with the inner side surface of one of the side sills, thereby strengthening a connection of three types of these floor frame members to increase the rigidity of a rear portion of a vehicle cabin for reducing undesirable mechanical vibrations.
In recent years, there has been proposed molding techniques for extruding a lightweight metal such as aluminum alloy in a longitudinal direction of a vehicle body to form a front floor having a closed hollow structure for decreasing the weight while increasing the rigidity of the vehicle body.
Using the extruded front floor increases an impact energy absorption and maintains a cabin space for a passenger by decreasing a lateral deformation of the front floor, since the front floor is extruded in a longitudinal direction and the impact from a center pillar studded on a side sill is perpendicular to each other, so the buckling deformation from the impact is distributed to a wide range of the floor by longitudinal stiffeners of the floor.
To attain this impact distribution ideally, a base portion of the center pillar lower end rotates into the cabin pivoted center pillar upper end, while maintaining its inner surface substantially parallel to a longitudinal body line. But the suggested three structure member gathering high strength structure which is fixed each other (the side sill, the rear sheet cross member and the rear side member) has a possibility to prevents deformation of the side sill or the front floor rear part and may prevent an ideal buckling deformation mode of the floor.
To attain this ideal impact distribution, a base portion of the center pillar lower end rotates into the cabin as it is pivoted about the center pillar upper end, while maintaining its inner surface substantially parallel to a longitudinal body line. But the suggested three structure member gathering high strength structure which is fixed each other (the side sill, the rear sheet cross member and the rear side member) may prevent deformation of the side sill or the front floor rear part and may prevent an ideal buckling deformation mode of the floor.
It is therefore a principal object of the present invention to improve the prior art.
It is another object of the present invention to provide a floor structure for an automotive vehicle which is designed to increase an absorbed amount of energy of impact acting on a vehicle body upon occurrence of a side collision without sacrificing the volume of a cabin for vehicle occupants and producing a buckling deformation mode of the floor.
According to one aspect of the invention, there is provided a vehicle floor which comprises (a) a front floor formed in extrusion, the front floor being so oriented that a direction of the extrusion is in parallel to a longitudinal direction of a vehicle; (b) a rear floor joined to a rear end of the front floor; (c) side sills disposed on sides of the front floor, each of the side sills extending in the longitudinal direction of the vehicle and having an extension projecting backward from the front floor; (d) a rear seat cross member having a length extending in a width-wise direction of the vehicle, the rear seat cross member being disposed on a connection of the rear floor to the front floor extending in the width-wise direction of the vehicle; (e) rear side members disposed on sides of the rear floor, extending in the longitudinal direction of the vehicle; (f) pillars secured on the side sills above the rear seat cross member; and (g) joint members each of which has a closed hollow structure and joins the extension of one of the side sills, one end of the rear seat cross member, and a front end of one of the rear side members, each of the joint members being installed between one end of the rear seat cross member and one of the side sills and having a lower-rigidity region formed adjacent the end of the rear seat cross member in the width-wise direction of the vehicle.